What was found
CLT - FLIGHT DEPARTED DCA, EN ROUTE TO FLL, WITH THE NR 1 ENGINE A-LOOP FIRE DETECTION ON MEL 26-2A. DURING CRUISE, THE NR 1 ENGINE B-LOOP FAULT LIGHT ILLUMINATED. CREW PERFORMED FIRE TEST AND HANDLE WOULD NOT TEST IN B-LOOP. WITH NO FIRE PROTECTION ON THE NR 1 ENGINE, FLIGHT DIVERTED TO CLT AND LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE TROUBLESHOT NR 1 ENGINE -A- AND -B- LOOPS IN ASSOCIATION WITH MM 26-11-00-1, FIGURE 101. ALSO CHECKED EACH INDIVIDUAL LOOP. ALL CHECK GOOD. REMOVED AND REPLACED NR 1 ENGINE CORE HARNESS PER MOC REQUEST. OPERATIONAL CHECK OF FIRE WARNING OK. ACCOMPLISHED ENGINE TEST FOR HARNESS CHANGE PER MM 71-00-00. CLEARED MEL 26-2A FOR NR 1 ENGINE -A-